The invention provides a groove-type MOS (Metal-Oxide-Semiconductor) device and a manufacturing method thereof. The groove-type MOS device at least includes a first conductive heavily doped substrate,a first conductive lightly doped epitaxial layer on the first conductive heavily doped substrate, a plurality of first conductive source regions, a plurality of grooves, a gate oxide layer and a polysilicon gate which are formed in the each groove, a second conductive lightly doped body region formed on the upper portion of the first conductive lightly doped epitaxial layer, a cellular region contact hole formed in the second conductive lightly doped body region, an insulating dielectric block covering the polysilicon gate in the groove of the cellular region, a second conductive heavily doped body contact region formed between two adjacent first conductive source regions of the cellular region, and a metal source electrode formed in the contact hole of the cellular region, wherein the plurality of first conductive source regions and the plurality of grooves are formed on the upper portion of the first conductive lightly doped epitaxial layer at intervals. The groove-type MOS device can guarantee stability of the device while improving the device density and reducing the conduction resistance.